Ellipsoidal Magnetite Nanoparticles: A New Member of Magnetic-Vortex Nanoparticles Family for Efficient Magnetic Hyperthermia
The development of magnetic iron oxide nanoparticles with novel topological magnetic domain structure, such as vortex-domain structure, is a promising strategy to improve the application performance of conventional superparamagnetic iron oxides while maintaining their good biocompatibility. Here, we fabricated a new kind of magnetic-vortex nanoparticles, ellipsoidal magnetite nanoparticles (EMPs), for cancer magnetic hyperthermia. The magnetization configurations and switching behaviours of the EMPs were analyzed by analytical simulation and Lorentz TEM, demonstrating the magnetic vortex structures of both single and coupled EMPs. The EMPs treatment of 4T1 cells exposed to an alternating magnetic field (AMF) induced a significant decrease in the cell viability by ~51.5%, which indicated a much higher cytotoxic effect in comparison with commercial superparamagnetic iron oxides (Resovist, ~12.0%). In addition, in vivo high efficacy of 4T1 breast tumor inhibition was also achieved by using EMPs-mediated magnetic hyperthermia. Our results not only provide a new type of magnetic-vortex nanoparticles for efficient hyperthermia, but also enrich the family of magnetic iron oxides nanoparticles for various biomedical applications.